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PubMed1998

Hydroxamate iron complex with phenoloxidase activity acting on lignin and chlorolignins.

The properties of a siderophore model, acetohydroxamic acid (AHA), of desferral were studied. The pH, ionic strength, and AHA/Fe(III) ratios for o-dianisidine oxidation were optimized. Phenoloxidase activity of hydroxamates/Fe(III) acting on o-dianisidine at pH 7.0 and pH 3.0 was observed. Under these conditions, AHA was able to reduce Fe(III) to Fe(II) followed by ferrozine complexation. AHA/Fe(III) complex degraded lignin and chlorolignins from kraft effluent E1 65% and 85%, respectively, after 24 h.

Biodegradation, Environmental↗
PubMed1998

Iron-binding catechols oxidating lignin and chlorolignin.

Iron-chelating low-molecular-weight compounds or catecholate siderophores have been suggested to be involved in wood biodegradation. To help in understanding the mechanism involved in the enzyme-like activity of catecholate siderophores, the oxidative properties of 2,3-dihydroxybenzoic acid (DHBA) and 3, 4-dihydroxyphenylacetic acid (DHPAA) chelated with iron were studied. The pH and catechol/Fe(III) ratios were optimized for o-dianisidine oxidation, obtaining a maximum at pH 7.0, in the absence of buffer, and a catechol/Fe(III) ratio of 1:2 to DHBA and 1:1 to DHPAA was found. Under these conditions, the catechols were able to reduce Fe(III) to Fe(II) acting like siderophore models. The Fe(III) complex of DHBA and of DHPAA degraded dioxane-lignin in 60% after 2 h and 85% after 24 h, respectively. DHBA/Fe(III) oxidized the bleaching effluent (E1) in 80% in 5 min under the studied conditions.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1999

A two-component tetrachlorohydroquinone reductive dehalogenase system from the lignin-degrading basidiomycete Phanerochaete chrysosporium.

Tetrachloro-1,4-hydroquinone (TClHQ) is an intermediate in the degradation of pentachlorophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium. Two enzymes required for the reductive dehalogenation of TClHQ to trichlorohydroquinone (TrClHQ) were identified in cell-free extracts of P. chrysosporium. In the presence of GSH, a membrane-bound enzyme converted TClHQ to the glutathionyl conjugate of TrClHQ (GS-TrClHQ). This membrane-bound glutathione transferase was specific for GSH as a cosubstrate. In the second step of the reductive dehalogenation reaction, a soluble enzyme fraction converted GS-TrClHQ to TrClHQ in the presence of GSH, cysteine, or dithiothreitol. Thus, this second enzyme appears to be a GS-conjugate reductase. These two enzyme fractions, working in tandem, also reductively dehalogenated TrClHQ and 2,6-dichlorohydroquinone, which are intermediates in the degradation of chlorophenols by this organism.

Cell Fractionation↗
PubMed1995

Comparison of the toxicity of various lignin-related phenolic compounds toward selected fungi perfecti and fungi imperfecti.

A selection of 88 micromycetes belonging to various taxonomic groups was grown on malt-agar medium containing different lignin-related phenolic compounds (ferulic, protocatechuic, syringic and vanillic acids, catechol, guaiacol, and phenol) at concentrations ranging from 100 to 1000 mg/liter. Growth and morphological changes were recorded after 15 days of incubation. Behavior of fungi in contact with the different phenolics were compared. Some strains were very sensitive and might constitute specific or general bioindicators of pollution. The relationships between origin of isolates or constitutive phenoloxidase activity and resistance or sensitivity of fungi to phenolics were researched. No evidence of implication of these two parameters was found.

Culture Media↗
PubMed1991

cDNA cloning, sequence analysis and seasonal expression of lignin-bispecific caffeic acid/5-hydroxyferulic acid O-methyltransferase of aspen.

A cDNA clone (Ptomt 1) encoding a lignin-bispecific O-methyltransferase (OMT) was isolated by immunological screening of a lambda gt11 expression library prepared from mRNA of developing secondary xylem of aspen (Populus tremuloides). Nucleotide sequence analysis of Ptomt1 revealed an open reading frame of 1095 bp which encodes a polypeptide with a predicted molecular weight of 39,802, corresponding well with the size of the OMT polypeptide estimated by SDS-PAGE. Authenticity of Ptomt1 was demonstrated in part by detection of OMT activity and protein in extracts of Escherichia coli cultures transformed with a plasmid construct containing Ptomt1. In addition, peptides produced from a proteolytic digest of purified OMT and sequenced by automated Edman degradation matched to portions of the deduced amino acid sequence of Ptomt1. Comparison of this sequence to amino acid sequences of OMTs of diverse species identified regions of similarity which probably contribute to the binding site of S-adenosyl-L-methionine. Tissue-specific expression was demonstrated by northern analysis which showed that Ptomt1 hybridized to a 1.7 kb transcript from aspen developing secondary xylem and by tissue printing of aspen stems in which only the outer layer of xylem bound the antibody. A biphasic pattern of gene expression and enzyme activity for OMT was observed from xylem samples of aspen during the growing season which suggests linkage between gene expression for a monolignol biosynthetic enzyme and seasonal regulation of xylem differentiation in woody plants.

Amino Acid Sequence↗
PubMed1998

Degradation of polychlorinated biphenyl mixtures by the lignin-degrading fungus Phanerochaete chrysosporium.

Degradation of lower-chlorinated and higher-chlorinated PCB congeners (Delor 103 and Delor 105 as equivalents of Aroclor 1242 and Aroclor 1254, respectively) by the white-rot fungus Phanerochoete chrysosporium was investigated in N-limited and non-limited media. No degradation of either Delor 103 or Delor 105 was found in a N-limited medium 9 d after their addition whereas in the non-limited medium during the same period their levels dropped by 55 and 58%, respectively. The degradation was non-specific and no significant differences in the degradation of di-, tri-, tetra-, penta-, hexa-, and hepta-congeners were found. No activity of Mn-dependent peroxidase (MnP) or lignin peroxidase (LiP) was detectable in the non-limited medium. We assume that the degradation of PCBs by P. chrysosporium is relatively non-specific, takes place under non-limited conditions and is independent of the activities of MnP or LiP.

Aroclors↗
PubMed1979

Antibiotic properties of lignin components.

Inhibitory effects of compounds with guaiacyl and syringyl structure, representing the structure of native lignin, were studied on model cultures of bacteria, yeasts, yeast-like microorganisms and moulds. Isoeugenol exhibited the most pronounced inhibitory effect on growth of the studied microorganisms.

Anti-Bacterial Agents↗
PubMed2004

Degradation of 4-nitrophenol by the lignin-degrading basidiomycete Phanerochaete chrysosporium.

The fungal metabolism of 4-nitrophenol (4-NP) was investigated using the lignin-degrading basidiomycete, Phanerochaete chrysosporium. Despite its phenolic feature, 4-NP was not oxidized by extracellular ligninolytic peroxidases. However, 4-NP was converted to 1,2-dimethoxy-4-nitrobenzene via intermediate formation of 4-nitroanisole by the fungus only under ligninolytic conditions. The metabolism proceeded via hydroxylation of the aromatic ring and methylation of phenolic hydroxyl groups. Although the involvement of nitroreductase in the metabolism of 2,4-dinitrotoluene by many aerobic and anaerobic microorganisms including P. chrysosporium has been reported, no formation of 4-aminophenol was observed during 4-NP metabolism. The formation of 1,2-dimethoxy-4-nitrobenzene was effectively inhibited by exogenously added piperonyl butoxide, a cytochrome P450 inhibitor, suggesting that cytochrome P450 is involved in the hydroxylation reaction. Thus, P. chrysosporium seems to utilize hydroxylation and methylation reactions to produce a more susceptible structure for an oxidative metabolic system.

Biodegradation, Environmental↗
PubMed2000

Polymerization of guaiacol by lignin-degrading manganese peroxidase from Bjerkandera adusta in aqueous organic solvents.

Lignin-degrading manganese (II) peroxidase (MnP) purified from the culture of a wood-rotting basidiomycete, Bjerkandera adusta, was used in the polymerization of guaiacol. MnP was found to catalyze polymerization of guaiacol in 50% aqueous acetone, dimethyl formamide, methanol, ethanol, dioxane, acetonitrile, ethylene glycol and methylcellosolve. Maximum yield of polyguaiacol was achieved in 50% aqueous acetone. The weight average molecular weight (Mw) of the polymer was estimated to be 30,300 by gel permeation chromatography. However, matrix-assisted laser desorption ionization time of flight mass spectroscopy (MALDI-TOF-MS) analysis gave a more reliable Mw of 1,690. IR, 13C-NMR, MALDI-TOF-MS and pyrolysis GC-MS analyses showed the presence of C-C and C-O linkages and quinone structure in polyguaiacol. It was also indicated that polyguaiacol has a methoxy-phenyl group as the terminal moiety. This suggests that polyguaiacol is a branched polymer in which guaiacol units are cross-linked at the phenolic group. Thermal gravimetric and differential scanning calorimetric analyses were also carried out. MnP also catalyzed the polymerization of o-cresol, 2,6-dimethoxyphenol and other phenolic compounds and aromatic amines. Mw of these polymers ranged from around 1,000 to 1,500.

Basidiomycota↗
PubMed2001

Degradation of diphenyl ether herbicides by the lignin-degrading basidiomycete Coriolus versicolor.

Under ligninolytic conditions, the white-rot basidiomycete Coriolus versicolor metabolized chloronitrofen (2, 4, 6-trichloro-4'-nitrodiphenyl ether; CNP) and nitrofen (2, 4-dichloro-4'-nitrodiphenyl ether, NIP), which constitute the largest class of commercially produced diphenyl ether herbicides. The pathway of CNP degradation was elucidated by the identification of fungal metabolites upon addition of CNP and its metabolic intermediates. The metabolic pathway was initially branched to form four metabolites--2, 4, 6-trichloro-3-hydroxy-4'-nitrodiphenyl ether, 2, 4-dichloro-6-hydroxy-4'-nitrodiphenyl ether, NIP, and 2, 4, 6-trichloro-4'-aminodiphenyl ether--indicating the involvement of hydroxylation, oxidative dechlorination, reductive dechlorination, and nitro-reduction. Of these reactions, hydroxylation was relatively major compared to the others. Extracellular ligninolytic enzymes such as lignin peroxidase, manganese peroxidase and laccase did not catalyze the oxidation of either CNP or NIP. Piperonyl butoxide, an inhibitor of cytochrome P450, suppressed fungal oxidation of CNP and NIP to their hydroxylated products. The inhibition resulted in increasing the amount of reductively dechlorinated and nitro-reduced products. These observations strongly suggest that basidiomycetes may possess a mechanism for a strict substrate recognition system and a corresponding metabolic response system to effectively degrade environmentally persistent aromatic compounds.

Basidiomycota↗
PubMed2002

Relationship of growth cessation with the formation of diferulate cross-links and p-coumaroylated lignins in tall fescue leaf blades.

We examined relationships among cell wall feruloylation, diferulate cross-linking, p-coumarate deposition, and apoplastic peroxidase (EC 1.11.1.7) activity with changes in the elongation rate of leaf blades of slow and rapid elongating genotypes of tall fescue ( Festuca arundinacea Schreb.). Growth was not directly influenced by ferulic acid deposition but leaf elongation decelerated as 8-5-, 8- O-4-, 8-8-, and 5-5-coupled diferulic acids accumulated in cell walls. Growth rapidly slowed and stopped with the deposition of p-coumarate, which is primarily associated with lignification in grass cell walls. Accretion of ferulate, diferulates and p-coumarate continued after growth ended, into the later stages of secondary wall formation. The concentration of 8-coupled diferulates dwarfed that of the more commonly measured 5-5-coupled isomer, suggesting that the latter dimer is a poor indicator of diferulate cross-linking in cell walls. Further work is required to clearly demonstrate the role of diferulate cross-linking and p-coumaroylated lignins in the cessation of leaf growth in grasses.

Cell Wall↗
PubMed2002

Biodegradation and biological treatments of cellulose, hemicellulose and lignin: an overview.

In nature, cellulose, lignocellulose and lignin are major sources of plant biomass; therefore, their recycling is indispensable for the carbon cycle. Each polymer is degraded by a variety of microorganisms which produce a battery of enzymes that work synergically. In the near future, processes that use lignocellulolytic enzymes or are based on microorganisms could lead to new, environmentally friendly technologies. This study reviews recent advances in the various biological treatments that can turn these three lignicellulose biopolymers into alternative fuels. In addition, biotechnological innovations based on natural delignification and applied to pulp and paper manufacture are also outlined.

Biodegradation, Environmental↗
PubMed1987

Enzymatic synthesis of lignin: purification to homogeneity of the three O-methyltransferases of tobacco and production of specific antibodies.

Three o-diphenol-O-methyltransferases (OMTs; EC 2.1.1.6) involved in the biosynthesis of lignin have been purified to homogeneity from tobacco leaves. Seven different fractionation steps which included (NH4)2 SO4 precipitation, conventional low-pressure chromatography on Ultrogel AcA34 and DEAE-cellulose columns, high-performance liquid chromatography (HPLC) on three different supports (Mono Q, Mono P, and TSK G-3000 SW columns), and finally preparative electrophoresis were necessary. At each step of purification, the protein content of the enzymatic fractions was analyzed by electrophoresis on polyacrylamide gels under denaturing conditions. Purified OMT I appeared on sodium dodecyl sulfate-polyacrylamide gel as a doublet with electrophoretic mobilities corresponding to molecular weights of 38,500 +/- 2000 and 39,500 +/- 2000. The other two enzymes migrated as single but rather broad bands with molecular weights of 42,000 (OMT II) and 43,000 (OMT III). Polyclonal antibodies were raised in rabbits. The titers of antibodies were measured by an indirect enzyme-linked immunosorbent assay method, and their specificity was demonstrated by immunoblotting enzyme preparations at different stages of purification. Immunodetection of the three enzymes with a specific antiserum suggested serological relationships between the three OMTs of tobacco.

Animals↗
PubMed1988

Degradation mechanisms of phenolic beta-1 lignin substructure model compounds by laccase of Coriolus versicolor.

Phenolic beta-1 lignin substructure model compounds, 1-(3,5-dimethoxy-4-hydroxy-phenyl)-2-(3,5-dimethoxy-4-ethoxyphenyl)propa ne-1, 3-diol (I) and 1-(3,5-dimethoxy-4-ethoxyphenyl)-2-(3, 5-dimethoxy-4-hydroxyphenyl)propane-1,3-diol (II) were degraded by laccase of Coriolus versicolor. Substrate I was converted to 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-(3,5-dimethoxy-4-ethoxyphenyl)-3- hydroxypropanone (III), 1-(3,5-dimethoxy-4-ethoxyphenyl)-2-hydroxyethanone (IV), syringaldehyde (V), 1-(3,5-dimethoxy-4-ethoxyphenyl)-3-hydroxypropanal (VI), 2,6-dimethoxy-p-hydroquinone (VII), and 2,6-dimethoxy-p-benzoquinone (VIII). Furthermore, incorporations of 18O of 18O2 into ethanone (IV) and 18O of H218O into hydroquinone (VII) and benzoquinone (VIII) were confirmed. Substrate II gave 1-(3,5-dimethoxy-4-hydroxyphenyl)ethane-1, 2-diol (IX), 1-(3,5-dimethoxy-4-hydroxyphenyl)-2-hydroxyethanone (X), and 3,5-dimethoxy-4-ethoxybenzaldehyde (XI). Also 18O of H218O was incorporated into glycol (IX) and ethanone (X). Based on the structures of the degradation products and the isotopic experiments, it was established that three types of reactions occurred via phenoxy radicals of substrates caused by laccase: (i) C alpha-C beta cleavage (between C1 and C2 carbons); (ii) alkyl-aryl cleavage (between C1 carbon and aryl group); and (iii) C alpha (C1) oxidation.

Basidiomycota↗
PubMed1989

Inhibition of the infectivity and cytopathic effect of human immunodeficiency virus by water-soluble lignin in an extract of the culture medium of Lentinus edodes mycelia (LEM).

Inhibition of the infectivity and cytopathic effect of human immunodeficiency virus type 1 (HIV-1) by the immunoactive fractions obtained from LEM, which is an extract of the culture medium of Lentinus edodes mycelia, is reported. A purified fraction, EPS4, obtained from LEM by ethanol precipitation followed by hydrophobic chromatography and gel filtration chromatography completely inhibited the HIV-1 induced cytopathic effect in vitro at concentrations of greater than or equal to 10 micrograms/ml. Chemical and spectral analysis revealed that EPS4 is composed of water-soluble lignins containing minor amounts of protein (3.2%) and sugars (12.2%). Taken together with the previously reported observation that EPS4 promotes the activation of macrophages and the proliferation of bone marrow cells, the fraction appears to possess both an immunostimulating activity and an anti-HIV effect in vitro.

Amino Acids↗
PubMed1988

Soluble lignin-carbohydrate complexes from sheep rumen fluid: their composition and structural features.

Lignin-carbohydrate complexes, isolated from cell-free rumen fluid of sheep, consisted of polyphenolic material in association with carbohydrate (5.5%) and protein (1.8%). No separation of carbohydrate from the other components could be effected. The complexes showed a bimodal distribution of molecular size with the higher-molecular-weight fraction richer in carbohydrate. Methylation analysis indicated a wide range of linkages and a high proportion of terminal sugars. Reducing sugars were found in the complexes, particularly in the low-molecular-weight fraction (approximately 25%), suggesting that ether linkages to the phenolics were also present.

Animals↗
PubMed1990

A novel enzymatic decarboxylation of oxalic acid by the lignin peroxidase system of white-rot fungus Phanerochaete chrysosporium.

Oxidation of veratryl alcohol by lignin peroxidase (LiP) was potently inhibited by oxalic acid. The inhibition analysis with Lineweaver-Burk plots clearly showed that the type of inhibition is non-competitive. The enzymatic oxidation of veratryl alcohol in the presence of 14C-oxalic acid yielded radioactive carbon dioxide. The results indicate that the apparent inhibition of LiP is caused by reduction of the veratryl alcohol cation radical intermediate back to the substrate level by oxalate, which is concomitantly oxidized to carbon dioxide.

Benzyl Alcohols↗